Under the optimized conditions, all the samples available were
subjected to MEKC analysis. Fig. 5 shows the electropherograms
obtained for a fruit nectar with added vitamins (A), a sport drink (B)
and an energy drink (C). A summary of the vitamin contents found
for all the drinks analysed is presented in Table 2. The analysis of
the energy drinks (ED) showed that the content of particular ingredients
in these drinks was diversified. In general, the found
levels of B vitamins were similar (or almost the same) as the values
on the product labels. However, sample ED1 showed a content of
vitamin C lower than that labelled. This value might be caused by
losses in storage and temperature, which is particularly problematic
for vitamin C (easy oxidation). In all examined ED, the declared
levels of B12 vitamin (0.38e2.5 mg/100 mL) were below the LOQ,
which made not possible its determination simultaneously with
the other vitamins. Regarding to the sport drinks (SD), details about
vitamin composition in product labels were not given, and only
ascorbic acidwas found as the main vitamin component. In fortified